Abstract: In the field of energy storage technologies, foreign countries started early, more achievement and experience in engineering project. Domestic energy storage technologies started late. In the distributed generation, using only one type energy storage is difficult to give good power performance for PV system. Based on our company grid-connected PV system photovoltaic with Li-ion battery and ultra-capacitor as hybrid energy storage system, it combined with the energy storage type of fast response characteristic and large capacity storage characteristics. The storage system controller coordinated power control between the energy storages and other power equipment in the system, which made the grid-connected power on demand and under control. The system can effectively increase the power output ability of PV generation system, decrease the frequency of charging and discharging for energy storage system, greatly extend the battery cycle life, has good application and popularization value.

Key words: combined storage, grid-connected PV, storage system controller